Open deck trailers for being towed behind a towing vehicle are commonly available in two varieties. One variety is a deck over configuration in which the deck surface of the trailer is positioned at or above the wheel height of the trailer so that the deck surface is continuous across the wheels. This type of trailer is convenient for side loading the trailer with pallets from a fork lift for instance as the weight of the material loaded onto the trailer can be centered at the wheel axle without interference of the wheel height interrupting the deck surface.
Alternatively, trailers are available in a deck between configuration in which the deck surface is recessed below a height of the wheels and spans between the wheels, thus limiting the overall width of the deck surface at the wheel location. This configuration is particularly useful for lowering the overall height of the deck surface to permit more convenient loading as a ramp when positioning a vehicle on the trailer for instance and for lowering the overall height of the load on the trailer.
To assist in lowering the deck height for loading, many trailers are known to have wheels supported on a bell crank arrangement operated by a lift cylinder to control the wheel height. Various examples are disclosed in U.S. Pat. No. 4,943,202 to Galloway, U.S. Pat. No. 6,135,700 to Collins, U.S. Pat. No. 4,008,902 to Dill, U.S. Pat. No. 2,762,631 to Entz and U.S. Pat. No. 3,335,887 to Snook. In each instance however the load of the trailer is carried by the lift cylinder of the bell crank arrangement so that safe operation is fully dependent upon the proper operation of the lift cylinder. In general no additional load support is provided separate of the lift cylinder to safely ensure that the deck is properly supported in relation so the wheels. Furthermore, all of the above examples permit only a single transport height and cannot be operated in either a deck over configuration or a deck between configuration in use. Consumers are thus required to purchase two separate trailer configurations if features of both a deck over configuration and a deck between configuration are desired.
Canadian patent 1,283,673 to Orr discloses a trailer in which the deck frame is similarly supported on the wheels by a bell crank arrangement dependent upon a lift cylinder to control height of the deck relative to the wheels. The trailer cannot be operated in a deck over configuration. As there is no additional load support, the load being carried relies heavily on the lift mechanism in order to avoid failure.